RFR: 8326227: Rounding error that may distort computeNextGaussian results [v2]

[Chris Hennick]

> This provides a slightly more accurate bounding limit for `computeNextExponentialSoftCapped` when the computed bound is greater than `(1.0p53 - 1.0) * DoubleZigguratTables.exponentialX0`. This could cause the `while (computeNextExponentialSoftCapped(rng, limit) < limit)` check in `computeNextGaussian` on line 1402 to always be true, making the `nextGaussian` runtime unbounded in the worst case.

Chris Hennick has updated the pull request incrementally with one additional commit since the last revision:

  Tweak boundary cases and add unit test

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Changes:
  - all: https://git.openjdk.org/jdk/pull/17703/files
  - new: https://git.openjdk.org/jdk/pull/17703/files/8af150e0..e68d03eb

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=17703&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=17703&range=00-01

  Stats: 40 lines in 2 files changed: 35 ins; 0 del; 5 mod
  Patch: https://git.openjdk.org/jdk/pull/17703.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17703/head:pull/17703

PR: https://git.openjdk.org/jdk/pull/17703